In an energy transitions era, the citizens tend to be increasingly considered as actors of the energy system. This situation reinforces in turn the importance of public participation processes into energy policy or legislation design. In 2012-2013, a significant public participation process in the field of energy policy was organised in France, named National Debate on the Energy Transition. From the beginning, it was proclaimed that its results would be integrated into a flagship energy transition act, which did happen with the adoption of the Energy Transition for Green Growth Act of 2015. This paper provides an overview of the organisation of this public debate and of the integration of its outcome into the Energy Transition Act. The experience of France can serve for other countries engaged in a process of transition towards a more sustainable society and especially towards a massive change of their energy mix. It addresses the successes as well as the failures of the French case and provides some key learning points to enhance the public participation into the Law-making process concerning the energy transition.